Conventionally, a switch reluctance motor (SR motor) where both a rotor and stator include salient poles, which causes non-sine wave currents to flow in field windings wound on the salient poles of the stator and rotationally drives the rotor by magnetic attraction forces of the field windings is known. This motor has such a feature that since laminated electromagnetic steel plates are used for the rotor, there is not such a problem that heat generation or heat demagnetization of the rotor occurs, and a high speed rotation is possible at a low cost. However, in a two-phase drive SR motor, when the salient poles of the rotor and the stator are completely opposed to each other, inductance change in a rotation direction does not occur, so that a torque does not occur. Therefore, a stepped gap type SR motor or a cam type SR motor which has solved such a problem by providing a step difference in a length of the rotor salient pole in a rotation direction or changing the rotor salient pole in a taper shape to change induction in the rotation direction has been introduced, but since a rotation direction where the inductance changes is limited to one direction in these motors, a reverse rotation is difficult therein. Further, a switched reluctance motor composed of a first switched reluctance motor section driving at three or more phases and a second switched reluctance motor section driving a two phases has been proposed (see Patent Document 1). In the three-phase switched reluctance motor, however, since a torque is generated in such an aspect that the salient poles of the rotor move relative to the salient poles of the excited stator such that the reluctance becomes minimal, the torque is pulsated, so that when a starting torque is small and a load is large depending on the position of the rotor, rotation does not take place or a large rotation fluctuation may occur. In addition, when reverse rotation is forced, the salient poles overlap with each other, and switching of an exciting phase is further performed after going pass, so that a case that starting cannot be made takes place. Therefore, a switched reluctance motor where three rotation position sensors for the rotor are provided and combination patterns of 6 kinds of position signals obtained from the three sensors are changed for each rotation of 15° of the rotor has been proposed (see Patent Document 2).
Further, as a method for detecting a rotation position of a rotor body, a method for capturing inductance changes of three coils where magnetic flux is obstructed by a rotor rotating in a synchronous manner, a method for detecting magnetic fields of magnets arranged on a rotating body so as to be opposed to rotation salient poles by Hall elements arranged around the rotating body so as to correspond to the rotation salient poles, and the like are disclosed (see Patent Documents 3, 7, 8).
On the other hand, in an electric automobile, a method for converting surplus kinetic energy during running time of the electric automobile into electricity to charge the same in a secondary battery, and the so-called regeneration braking where surplus kinetic energy during deceleration is converted to electricity to be collected and consumed are effective for suppressing energy consumption to elongate a running distance or enhancing an energy efficiency. Therefore, such a method is proposed that, when power generated by regeneration braking is charged into the battery, a capacity limitation value of an initial charging is set less than full charging such that the battery is not overcharged on a long downslope while an upper limit value of a vehicle speed is set so as to lower when charging reaches overcharging during running (see Patent Document 4). Further, such a method is proposed that by performing an integration processing of a toque, use of a regeneration torque is limited or inhibited to prevent the windings of the motor from overheating and sufficient vehicle performance is secured, after a high torque exceeding a reference value is outputted, and a such an inconvenience is solved that a current is limited due to rising of a winding temperature due to regeneration braking during hill descending and a torque required during hill ascending thereafter cannot be obtained (see Patent Document 5).
Further, such a method that for improving fuel consumption, only regeneration braking is used when a required braking force obtained by brake pedal operation is smaller than a regeneration braking force, while both regeneration braking and frictional braking are used when the required braking force is larger than the regeneration braking force, and a ratio of the regeneration braking force is made small when rapid barking is required, or the like is proposed (see Patent Document 6).
In the method described in Patent Document 1 or Patent Document 2, however, noises or vibrations may occur due to unbalance of a radial direction component of a torque acting on the rotor and a special logic circuit for combining a main excitation phase and a subsidiary excitation phase with each other in response to a rotation angle of the rotor is required. Further, in the methods disclosed in Patent Document 4 to Patent Document 6, there is such a possibility that, even if improvement of the energy efficiency or improvement of the fuel consumption can be achieved, when a driver familiar to an engine automobile relaxes and releases an acceleration pedal with a feeling similar to that to an engine brake, the driver steps on the brake pedal hastily from a feeling of anxiety when the regeneration braking does not function.
Therefore, the present applicant invented a non-sine wave driving motor which can obtain a low torque ripple with a high torque by detecting magnetic poles of magnets installed on a rotation body rotating in synchronism with a rotor by magnetic sensors such as Hall elements to detect a rotation position of the rotor and controlling excitation currents flowing in field windings wound on the magnetic poles of the stator while performing acceleration and deceleration with the same means and the same operation in order to obtain a feeling similar to the engine brake and got a patent of the invention (see Patent Documents 7 and 8).